A significant proportion of adults drink heavily and consequently are at risk for a variety of problems such as motor vehicle accidents, injuries, medical illnesses, work difficulties, and family dysfunction. In the past two decades, brief interventions have proven to be promising in reducing heavy drinking. The objective of this R21 application is to investigate ways of augmenting the effectiveness of brief interventions. Recent developments in treatments for alcoholism underscore the primacy of utilizing the social networks of heavy drinkers for enhancing drinking outcomes. However, few studies have examined the likelihood that involving the spouse/significant other in a brief motivation-based intervention with an individual heavy drinker may improve problem drinking outcomes. The long-term objective of this programmatic body of treatment outcome research is to enhance brief interventions for adult heavy drinkers. The specific aims of this treatment development proposal are to: 1) develop a treatment manual for conducting a brief Spouse/Significant Other Involved Motivational Interview (SIMI); 2) pilot test and refine the treatment manual on 10 patients in a primary care setting; and 3) collect assessed by comparing subjects in the SIMI and Assessment Control (AC) conditions on alcohol use and alcohol-related negative consequences at 3-months. We propose to supplement Motivational Interviewing, a brief intervention with demonstrated success in reducing heavy drinking, by including a spouse/significant other as a way of capitalizing on the potential effect of social support on drinking outcomes. Enhancing the efficacy of brief motivation-based interventions with heavy drinking adults provides a means to circumvent the development of chronic alcohol problems and alcohol-related negative consequences among this population.